MBP battery drain in sleep mode.

MBP early 2008

Running OS X 10.8.5

drain

Recently purchased a new battery and have noticed that the battery will loose all most all of its charge while in sleep mode in approximately 72 hours.

I vaguely recall that my battery would hold a charge in sleep state for much longer than that a few years back.

Am I mistaken or is there something that is causing the battery drain while in sleep mode. Is there a way to determine what's causing this and eliminate it?

TIA-

Jim P.